On Thu, Nov 08, 2001 at 03:02:15PM -0600, Mike Meyer wrote:
> Could you provide a pointer to where you found it? An explanation of
> why users need to reprogram their MAC's - which is rather unusual -
> would help quite a bit.

There are several possibilities:

* Users wish to replace a card but have it use the same MAC
  address due to filters, static arp entries, caches that take too
  long to expire, bootp entries that are based on MAC address, etc.
  For years cards had the MAC in a separate ROM to make this possible
  with a chip swap too.

* Some protocols (mostly all obsolete) required specific MAC
  addresses.

* Some clustering software switches MAC's from one machine to 
  another to make the switch transparent at layer 2.

Older cards could only answer a single MAC, a small multicast MAC
list, and the broadcast MAC.  I think most newer designs unify this
into a single "list of things I want", which could allow a card to
be multiple unicast MAC's at once.


-- 
       Leo Bicknell - [EMAIL PROTECTED] - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
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